As shown in the patent document 1, this kind of the power source device is configured to be connected to the light radiation device comprising a light source and an identification resistance whose resistance value differs for each type of the light source, and the type of the light source is automatically determined and the light source can be controlled to change the brightness of the electric light in accordance with the determined type of the light source.
If explained more concretely, the power source device has a voltage dividing resistance connected in series to the identification resistance, the divided voltage applied to the voltage dividing resistance is measured, and the type of the light source is determined based on the measured divided voltage value.
However, in the case that the type of the light source is determined based on the divided voltage value, it is necessary to select the identification resistance among a limited range of the resistance value in order for the divided voltage value to fall within the measurement range.
In addition, since the resistance value of the identification resistance contains a manufacturing error, if the resistance value of the identification resistance of each light source is close to each other, it is not possible to distinguish whether the difference in the measured divided voltage value appears due to the type of the light source or due to the manufacturing error of the identification resistance.
For this reason, the type of the resistance value that can be used as the identification resistance is limited so that the present structure can determine only limited types of the light source, and the number of these types is not satisfactory at all.